Missing: Drake Kramer, 21, of San Antonio, Texas has been missing for the last week. He was last seen at the Grand Canyon on Saturday

Search and rescue teams have been searching 285 square miles of the Grand Canyon for the last week, combing the area for a 21-year-old geology student who went missing there after sending a puzzling text message to his worried parents.

Drake Kramer of San Antonio, Texas was last spotted at the south rim of the Grand Canyon on Saturday, January 31.

He checked out of the Bright Angel Lodge the next morning and hasn't been seen by friends or family since.

His parents Robin and Brenda Kramer reported him missing on Monday, when they learned of the trip and received a text message from their son in which he said he 'needed to be with Mother Earth'.

'We don't know what his plans were. He may be hiking, we just don't know,' Kirby-Lynn Shedlowski of the Grand Canyon National Park told ABC News on Saturday.

Mr Kramer told My San Antonio that his son was in 'good spirits' the last time the two met on January 29 to see the film American Sniper.

'He works and had just started school,' Mr Kramer said. According to Drake's Facebook page, he works at Lowe's and studies geology at Northwest Vista College.

His parents say they lost contact with him for a few days, and when they reached out to his friends they said he was staying at a co-worker's house.

The Kramers texted their son on Sunday, asking about his whereabouts and learned that he had unexpectedly traveled more than 1,000 miles to Arizona.

Trail: The geology student checked out of this hotel at the south rim of the Grand Canyon on Sunday and hasn't been seen by family or friends since

Nature lover: Kramer's parents reported him missing on Monday after receiving a cryptic text message from him saying 'he needed to be with Mother Nature'. Pictured on the left during a 2013 trip to the Grand Canyon

Mr Kramer says it's 'completely out of character' for his son to pick up and leave without telling his parents. However, he is an experienced outdoorsman who has visited the park several times in the past. In pictures of the Grand Canyon posted to his Facebook page in August 2013, Drake wrote 'Great vacation which I coulda stayed'.

His parents started worrying for his safety on Monday, when he sent a cryptic text message.

'He indicated that he needed to be with Mother Earth,' My Kramer told AZ Central.